The present disclosure relates to a semiconductor device, and particularly a bipolar transistor.
In recent years, numerous integrated circuits (IC) have been mounted in electronic devices and have contributed to increasing compactness and multi-functionality of the electronic devices. In addition to passive elements such as a resistive element or a capacitive element, active elements such as a field effect transistor (FET), represented by a MOS (Metal Oxide Semiconductor) transistor, or a bipolar transistor are integrated in the integrated circuit. In particular, bipolar transistors are used in various applications such as audio, various sensors, display drivers, and the like.
The significant electrical characteristics of bipolar transistors are, for example, the current amplification factor, early voltage, and the like. In general, from the perspective of the circuit characteristics, a high current amplification factor and a high Early voltage are desirable. Specifically, for example, in a current mirror circuit or the like, in a case where the current amplification factor is high and the Early voltage is high, it is possible to increase the accuracy of the current which is generated. Several methods for increasing the Early voltage or current amplification factor have been disclosed. For example, in Japanese Unexamined Patent Application Publication No. 06-310526, a bipolar transistor to improve the current amplification factor has been disclosed.